Carburetor

ABSTRACT

A carburetor for an internal combustion engine has a plurality of passage means for providing fuel-air mixtures for the various operating ranges of the motor. Each of the passage means is formed to cause said fuel-air mixture to approach sonic velocity in its passage therethrough.

United States Patent 1191 August 1 June 4, 1974 1 1 CARBURETOR 3,143,401 8/1964 Lumhrecht 261/78 R 3,246,886 41966 G (1" 1'1. ..26139 D [761 Inventor: Paul Augus" Capellades 3,249,345 5/1966 261/39 D Barcelona 6, Spam 3,282,572 11/1966 Karlovitz 261/78 R 9 3,298,677 1/1967 Anderson 1 261/41 D [22] May 1972 3,523,680 8/1970 Bartholomew 261/23 A [21] Appl. No.: 249,556 3,544,083 12/1970 Currie 261/41 D 3,570,821 3/1971 Walker 261/41 D 3,664,648 5/1972 Seeley, .lr 261/D1G. 39 [52] U.S. Cl 261/39 D, 261/41 D, 261/65,

261N310 261/78 R, 123/119 R Primary ExaminerTim R. Miles {51] Int. Cl. F02m 1/04 Attorney Agent, Firm-AndruSQ SCealesy Starke &

[58] Field of Search 261/39 D, 41 D, 65, DIG. 39, Sawan [57] ABSTRACT [56] References Cited A carburetor for an internal combustion engine has :1

UNITED STATES PATENTS plurality of passage means for providing fuel-air mix- 1,727,568 9/1929 Sills 261/41 C tures for the various operating ranges of the motor, 1,736,239 4 4 C Each of the passage means is formed to ause 213171625 4/1943 Mallory 261/4' C fuel-air mixture to approach sonic velocity in its pas- 2,328,764 9/1943 Wirth Z61/D1G. 39 g therethrough 2,821,373 1/1958 Olson 261/78 R 3,110,750 11/1963 R0me0..... 261/78 R 18 Claims, 5 Drawing Figures 27 78 A \M 2 20 B ATENTEDM 4 Ian I V saw 1 or 2 Fig. I

CARBURETOR BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to an internal combustion engine carburetor having means for treating the fuel-air mixture for various operating conditions of the engine.

Recent developments in carburetor technology have brought, among other things, knowledge that numerous improvements may be derived when the fuel-air mixture is caused to flow through a region in which it approaches sonic velocity.

The carburetor is an atomization device which works according to the principal of speed atomization; that is, a cohesive liquid mass may be torn apart as a result of the relative speed between the liquid and surrounding air flow (friction). The greater the relative speed between the air and liquid the smaller the particles of liquid so formed. Gasoline may be so finely atomized that the drops as small as microns are formed. When so finely atomized, the gasoline will be carried in the suspended state in the intake air. It will further tend to remain in suspension and will not be flung out by centrifugal force in the bends in the air stream, thereby to form condensate.

While there are various constructions for carburetors in which fuel-air mixing takes place under sonic velocity conditions, these constructions tend to be somewhat radical in design and will require considerable testing to reduce to a practical embodiment and mode of action.

The present invention on the other hand is directed to an arrangement of carburetors of conventional design to provide sonic velocity mixing in all, or almost all, of the operating ranges of the engine from cold start, through idling and part load to full load. The carburetor of the present invention is simple and economical in construction. The very high flow speeds are attained by a corresponding narrowing of the flow passages and other suitable formations. The carburetor of the present invention is preferably equipped with a throttle valve (butterfly valve) but may be equipped with other types of flow control devices.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a vertical cross sectional view through the fuel-air mixture forming portion of the carburetor of the present invention including a throttle valve.

FIG. 2 is a horizontal cross sectional view of the carburetor taken along the line A-B of FIG. 1.

FIG. 3 is a fragmentary cross sectional view of a throttle valve of conventional construction in the barely open condition.

FIG. 4 is a fragmentary cross sectional view of a throttle valve constructed according to the present invention in the closed condition.

FIG. 5 is a fragmentary cross sectional view of a throttle valve constructed in accordance with the present invention in the slightly open position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Carburetor housing 1 contains main fuel-air mixing passage 2 in which is located throttle valve 3. Fuel, supplied from a conventional float housing or the like (not shown), enters through hole 4 forming a portion of the main nozzle system. The fuel flows into passage 5 defined by the inner cylindrical wall of pipe 6. Within pipe 6 is mounted insert 7 which, together with the inner wall of pipe 6 defines a fuel flow passage having, in the direction offuel flow, initially a converging. then a parallel, and then finally diverging cross section.

The outer wall of pipe 6 is tapered at the lower end. Tube 8 surrounds pipe 6, as shown in F IG. 1. Tube 8 is also tapered so as to form an area of converging cross section with the upper portions of pipe 6 and an area of uniform cross section with the tapering lower portion of pipe 6. Tube 8 is mounted in main fuel-air passage 2 so as to position the lower end of the tube in the restricted portion of air horn 9.

The main fuel nozzle system provides fuel through hole 10 and passage 11 to idle nozzle 12. Air for the idle mixture enters into passage 14 from air intake 13 and mixes with the fuel at nozzle 12 to provide an enriched idle mixture in passage 15. The idle mixture enters carburetor base 16 in passage 17 and through passage l8 and one or more holes 19 enters into slit 20. A measuring screw 21 by which the quantity of the idle mixture can be regulated is interposed in passages 17 and 18. Slit 20 has at the entrance from passage 18 a converging portion. In the middle of slit 20 is a parallel portion and thereafter a diverging portion.

Fuel from the float housing enters through passage 22 into standpipe 23 and passes from there through nozzle 24 into passage 25. Air from air intake 13 enters passage 25 through hole 26 to form a fuel-air mixture in passage 25. The composition of this mixture, which is utilized for cold starts is determined by the size relationship between nozzle 24 and air hole 26. A throttle valve 27 in passage 8 controls the supply of the fuel-air mixture in passage 25 to passage 30 and main fuel-air passage 2.

Under cold starting conditions, throttle valve 27 will be opened so that the cold starting mixture in passage 25 will flow through passages 28 and 30 into the main mixing passage 2 below throttle valve 3. The slit 30 is formed so as to have first a converging, then a parallel, and then a diverging portion in the flow direction between passage 28 and inlet 29 to the main mixing passage 2.

Throttle valve 3 is pivotally mounted in main mixing passage 2 on throttle valve shaft 31. When in the closed condition, its surfaces 32 and 33 lie against the inner wall of main air-fuel passage 2, as shown most clearly in FIG. 4. For this purpose, the surface 32 on the right, or higher side of the throttle valve, when viewed as shown in FIG. 4, lies above the horizontal center line of the valve. For similar reasons surface 33 on the left side of throttle valve 3 lies under the center line. On the right side of throttle valve 3 surface 34 is inclined under and away approximately 2030 from surface 32. On the left side of throttle valve 3 a similar, angled surface 35 is found above surface 33.

The mode of operation of a carburetor of the foregoing construction is such that it undertakes to produce sonic velocities during mixture formation for all operating ranges.

COLD STARTING Commencing use of the engine driven vehicle generally involves thestart up of a cold motor. In connection with cold starts it is important to note that because more strict US. laws regarding exhaust gas detoxification due to become effective about 1975 will approve such small quantities of carbon monoxide and hydrocarbons in exhaust gases, particular attention must be paid to fuel-air mixture formation under cold starting conditions.

There are arrangements for afterbuming the exhaust gas which meets such requirements. However, since these burners, whether of the catalytic or other type, require about 100 to 120 seconds from cold start to become active, the cold starting carburetor arrangement must create almost no condensate so that the motor in the cold condition will not provide objectionable excesses in the exhaust gas.

This is possibleonly when the mixture for cold starting is produced under sonicvelocities so that the fuel particles are finely misted and in the suspended state proportionatelydistributed in the intake of the cylinders.

Condensate formation on the cold walls of the carburetor and induction manifold bends must be carefully avoided.

The cold starting arrangement of the carburetor of the present invention fulfills the requirements specified above.

Slit 30, besides its flow formation characteristics is downwardly directed and formed as a broad slot. (see FIG. 2). This permits the finely atomized fuel mixture to form a similar broad band for entry into fuel-air passage 2 and for passage in a condensate and drop free manner to the individual cylinders.

IDLING Under idling conditions, the increased speed of the air may give rise to poor mixture formation. However, with the present invention, the intake air under idling conditions does not flow through the slightly open throttle valve. Rather, throttle valve 3 is closedand the intake air flows through slit 20. The necessary fuel for the idling condition mixture will mix with the intake air in one or more holes 19 and the quantity of the idling fuel-air mixture is determined by regulating screw 21.

The fuel in slit 20 preferably will be fed to the converging portion of the slit along with the intake air so that by means of the parallel portion of the slit sonic velocity will be attained and the fuel will be atomized to a fine mist while in the subsequent flow formation in the diverging part the mixture will be subjected to below sonic speed atomization.

Slit 20 is also designed with a downward slope in the direction of the main air-fuel mixing passage 2 so that the finely misted idling mixture may be supplied condensate and drop free to the cylinders without condensate forming impingement upon walls or the like.

The foregoing entry formation incorporates two of the latest scientific findings.

I. It has been shown that the fine atomizing of fuel to sizes under microns becomes advantageous and extensive when the passage for the mixtures is not higher than one millimeter.

It therefore becomes essential that slits and be formed as low, broad slots and that the entire quantity of fuel-air mixture for cold start and for idling conditions be fed therethrough.

One can also undertake the same through an annular space with an inner body insert but additional height is required. This is undesirable since carburetors should be sufficiently low in height that the engine compartment does not, on account of the carburetor, have to be enlarged.

2. Especially in the idling condition it is essential that the flow from slit 20 be located downstream from bypass hole 36 so that in spite'of the possibility of inade- TRANSITION With a normal throttle valve (see FIG. 3) there is located immediately below the lower most bypass hole 36 a free space under the throttle valve. The presence of this free space causes the high flow speed to immediately diminish. It has further been shown that with such a throttle valve, part of the fuel flows along under the same. An air vortex is formed there which through contact with the throttle valve and throttle valve shaft dislodges drops of fuel, some of which may be of considerable size.

The throttle valve of the present invention operates in a different manner. In the closed condition, throttle valve 3 lies with its surfaces 32 and 33 on the inner wall of main fuel-air mixing passage 2. The opening of throttle valve 3 as shown in FIG. .5 forms again a section of first converging and then diverging cross section in the area of the bypass holes and on' the opposite side of the throttle valve.

The flow of the intake air through this first converg ing and then diverging space between throttle valve 3 and the inner wall of fuel-air mixing passage 2 brings as a consequence the enhancement of the flow to sonic velocity resulting in a fine misting of the fuel under transient conditions as well as under cold starting conditions.

This fine misting and above described flow atomization may take place also in the part load range in which the throttle valve surfaces are not located adjacent the walls of the mixing passage.

PART LOAD AND FULL LOAD OPERATION Under part and full load operating conditions, fuel is provided out of the main nozzle system in hole 4. In accordance with the present'invention, this fuel is also subjected to special treatment, specifically passage through an area containing first a converging, then a parallel, and finally a diverging portion. This area is formed in this instance by pipe 6 and insert 7. By this means the fuel becomes atomizingly prepared and mixed with the fast flowing air existing at the exit of pipe 6. The fast flowing air is produced by the conical narrowing of pipe 6 which forms a first converging and then parallel air passage between the pipe and the tube 8 for bringing the air to sonic velocity. At the outlet of pipe 6, the fuel enters the main mixture under sonic velocity and the already previously excellently prepared fuel is additionally atomized to a fine mist in the intake air.

In the present invention, there is provided in all mixing portions first a converging, then a parallel, and then a diverging cross section to the flow passages. Examination has shown that through this arrangement, sonic velocity of the mixture is attained in all cases. In regard to the simultaneous or parallel operation of various elements of the invention, the quantity of fuel and mixture provided through the openings of the various elements is calibrated and determined by the cross sectional area of the parallel portions or narrowest portions of the element flow passages and not by some adjustable control apparatus.

With the fuel-air mixture so formed, which is finely misted, condensate and drop free, and perfectly homogeneous, it is possible to obtain the same mixture in all cylinders. It therefore becomes possible to obtain satisfactory running of the motor with mixture ratios of over :1 With such a mixture ratio, surplus oxygen is available in the exhaust gas. The exhaust gas is low in both carbon monoxide and the hydrocarbon factors. If deemed necessary or desirable, an exhaust gas of such a composition can be further combusted by a simple and economical afterburner to completely burn the small amounts of carbon monoxide and hydrocarbons.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

1 claim:

1. A carburetor for an internal combustion engine having a main fuel-air mixture passage and a cold start passage means for forming the cold start fuel-air mixture, each of said passages being formed so as to cause said fuel-air mixture to approach sonic velocity in its travel therethrough, said cold start passage means including a low, broad, slitlike channel having one end opening into said main fuel-air mixture passage and the other end receiving the cold start fuel-air mixture, said channel having first converging and then diverging portions in the direction of flow and a cross sectional area which determines the quantity of cold start fuel-air mixture provided to the main fuel-air mixture passage means.

2. The carburetor according to claim 1 further defined in that the main fuel-air mixture passage has have first converging and then diverging portions in the direction of flow.

3. The carburetor according to claim 1 including a main fuel-air mixture passage having a fuel nozzle means therein, said nozzle means being formed to have first a converging, then a parallel, and then a diverging cross section in the direction of flow.

periphery coacting with the inner wall of said passage, said periphery being beveled to form at least two different angled surfaces.

7. The carburetor according to claim 6 wherein when said throttle valve is in the closed position, one of said angled surfaces lies on the inner wall of said passage and another of said angled surfaces forms an angle of from 15-30 with the inner wall.

8. The carburetor according to claim 6 wherein said angled surfaces are so formed that upon opening said throttle valve, the surfaces form, with the inner wall of said main fuel-air mixture passage, a space having first a converging and then a diverging cross section.

9. The carburetor according to claim 1 including a main fuel-air mixture passage having a fuel nozzle means therein, said nozzle means being formed to have first a converging and then a diverging cross section in the direction of flow.

10. The carburetor according to claim 9 wherein said fuel nozzle means includes a discharge pipe having an insert therein for forming the desired cross section in the direction of flow.

11. The carburetor according to claim 9'including air flow means surrounding said fuel nozzle means and forming therewith an air passage which has an initial converging portion and thereafter parallel portion in the direction of flow.

12. The carburetor according .to claim 1 further including an idling operation passage means for forming the idling fuel-air mixture and for discharging same into said main fuel-air mixture passage.

13. The carburetor according to claim 12 wherein the openings of said first end of said cold start passage means and said first end of said idling operation passage means into said main fuel-air mixture passage are diametrically opposite.

14. The carburetor according to claim 12 wherein said idling operation passage means includes a low broad slitlike channel having one end opening into said main fuel-air mixture passage and the other end receiving the idle fuel-air mixture, said channel having first converging and then diverging portions in the direction of flow.

15. The carburetor according to claim 14 further defined in that the passage means have parallel portions interposed between said converging and diverging portions.

16. The carburetor according to claim 12 wherein said idling condition passage means channel opens into said main fuel-air mixture passage in a downwardly extending direction along the flow path.

17. The carburetor according to claim 16 including flow regulating means in said idling operation passage means.

18. The carburetor according to claim 16 wherein said main fuel-air mixture passage includes an idling condition bypass port opening into said main fuel-air mixture passage, said idling condition passage means opening into said main fuel-air mixture passage down stream of said bypass ports. 

1. A carburetor for an internal combustion engine having a main fuel-air mixture passage and a cold start passage means for forming the cold start fuel-air mixture, each of said passages being formed so as to cause said fuel-air mixture to approach sonic velocity in its travel therethrough, said cold start passage means including a low, broad, slitlike channel having one end opening into said main fuel-air mixture passage and the other end receiving the cold start fuel-air mixture, saiD channel having first converging and then diverging portions in the direction of flow and a cross sectional area which determines the quantity of cold start fuel-air mixture provided to the main fuel-air mixture passage means.
 2. The carburetor according to claim 1 further defined in that the main fuel-air mixture passage has have first converging and then diverging portions in the direction of flow.
 3. The carburetor according to claim 1 including a main fuel-air mixture passage having a fuel nozzle means therein, said nozzle means being formed to have first a converging, then a parallel, and then a diverging cross section in the direction of flow.
 4. The carburetor according to claim 1 including a main fuel air mixture passage having a flow control means therein.
 5. The carburetor according to claim 1 wherein said cold start passage means channel opens into said main fuel-air mixture passage in a downwardly extending direction along the flow path.
 6. The carburetor according to claim 1 including a main fuel-air mixture passage having a throttle valve pivotally mounted therein, said throttle valve having a periphery coacting with the inner wall of said passage, said periphery being beveled to form at least two different angled surfaces.
 7. The carburetor according to claim 6 wherein when said throttle valve is in the closed position, one of said angled surfaces lies on the inner wall of said passage and another of said angled surfaces forms an angle of from 15-30* with the inner wall.
 8. The carburetor according to claim 6 wherein said angled surfaces are so formed that upon opening said throttle valve, the surfaces form, with the inner wall of said main fuel-air mixture passage, a space having first a converging and then a diverging cross section.
 9. The carburetor according to claim 1 including a main fuel-air mixture passage having a fuel nozzle means therein, said nozzle means being formed to have first a converging and then a diverging cross section in the direction of flow.
 10. The carburetor according to claim 9 wherein said fuel nozzle means includes a discharge pipe having an insert therein for forming the desired cross section in the direction of flow.
 11. The carburetor according to claim 9 including air flow means surrounding said fuel nozzle means and forming therewith an air passage which has an initial converging portion and thereafter parallel portion in the direction of flow.
 12. The carburetor according to claim 1 further including an idling operation passage means for forming the idling fuel-air mixture and for discharging same into said main fuel-air mixture passage.
 13. The carburetor according to claim 12 wherein the openings of said first end of said cold start passage means and said first end of said idling operation passage means into said main fuel-air mixture passage are diametrically opposite.
 14. The carburetor according to claim 12 wherein said idling operation passage means includes a low broad slitlike channel having one end opening into said main fuel-air mixture passage and the other end receiving the idle fuel-air mixture, said channel having first converging and then diverging portions in the direction of flow.
 15. The carburetor according to claim 14 further defined in that the passage means have parallel portions interposed between said converging and diverging portions.
 16. The carburetor according to claim 12 wherein said idling condition passage means channel opens into said main fuel-air mixture passage in a downwardly extending direction along the flow path.
 17. The carburetor according to claim 16 including flow regulating means in said idling operation passage means.
 18. The carburetor according to claim 16 wherein said main fuel-air mixture passage includes an idling condition bypass port opening into said main fuel-air mixture passage, said idling condition passage means opening into said main fuel-air mixture passage down stream of said bypass ports. 